Amazon has finally revealed the size and growth of its cloud-computing division, called Amazon Web Services.

While posting its first-quarter earnings, the Jeff Bezos-led company for the first time detailed AWS financials. It had revenue of $1.57 billion during the 90-day period that ended on 31 March, with a profit of $265 million, meaning it was just as large - if not larger - than rival cloud service divisions. Bezos, the company's founder and CEO, described AWS as a $5 billion business that's growing fast.

"Born a decade ago, Amazon Web Services is a good example of how we approach ideas and risk-taking at Amazon. We strive to focus relentlessly on the customer, innovate rapidly, and drive operational excellence. We manage by two seemingly contradictory traits: impatience to deliver faster and a willingness to think long term," said Bezos in a published statement.

Investors are likely most excited about the disclosure of AWS’ finances, which have long remained under wraps. Critics had assumed AWS was not yet profitable and that Amazon’s core retail unit was stronger. Apart from AWS, other financials bits include net sales, which increased by 15 per cent to $22.72 billion yoy, and operating income, which increased by 74 percent to $255 million yoy.

In the first quarter, Amazon reported a loss of $57 million, or 12 cents per share. The average estimate of analysts was for a loss of 13 cents per share. And finally, Amazon said games and apps for its Fire TV grew "5x" since last year. As usual, Amazon didn't share specific numbers.

In reaction to these financial results, Amazon shares were up around 5 per cent in after hours trading. Check out Amazon's live-streamed conference call at 2:30 PM PST for more information and forward-looking statements.